Passive fire protection refers to the protection built into the design of a building to defend against the threat of fire. An example of passive fire protection involves enclosing areas with fire barriers. Fire barriers formed by fire resistant walls can effectively prevent the spread of fires from one section of a building to another. In this way, only the portion of the building in danger must be evacuated. Other portions separated from the danger by fire barriers will remain safe unless the situation worsens.
Fire doors are used to permit people to pass through a fire resistant wall to travel from one section of a building to another. If a fire door is left open during a fire, there will be a breach in the fire barrier, and the risk of fire spreading across the fire barrier will increase.
Fire doors may be automatically closed in the event of a fire. The fire door is held open by an electronic device during times when a fire condition is not detected. When power to the electronic device is switched off because of a fire, the fire door will close. In addition, emergency doors that normally remain locked by an electronic device may be automatically unlocked in the event of a fire by removing power to the electronic device. Fire doors and emergency doors that include these electronic latching systems require a considerable amount of power because the energized state of the system occurs nearly 100% of the time. A substantial portion of the cost of door holders and door locks is the cost of supplying constant power to the devices.
Further, in the event of a power outage, electronic latching systems often use battery backup systems. Because the standby states of these systems require continuous power possibly for long periods of time, large batteries are required for adequate operation of the battery backup systems.
What is needed is a system of electromagnetic door holder or door locks that conserves power, which will reduce the cost of system and increase the potential standby time for battery powered systems.